Inflatable insulating liners including phase change material

ABSTRACT

Abstract of Disclosure 
     An insulating liner is provided having an inflatable, double outer layer defining an interior container space for thermally-sensitive cargo.  A phase change material layer is formed upon or carried by a baffle material lying within the inflated layer.  The multiple layers forming the insulating liner are attached to one-another in a series of inflation seals that form a plurality of interconnected inflatable chambers which, when inflated, provide structural definition to the interior containment space.

Cross Reference to Related Applications

[0001] This application is a continuation-in-part of U.S. Application No. 09/156,208, filed September 17, 1998.

Background of Invention Field of the Invention

[0002] The present invention relates to thermally-insulated shipping containers and, more particularly, to shipping containers that are selectively inflatable. More specifically, the present invention relates to a pair of film layers having opposed reflective surfaces, and an optionally-interposed film baffle layer, that together define an inflatable envelope in the form of a flexible insulating bag.

Description of the Prior Art

[0003] In the transportation and distribution of products, both the product and the package define the "shipping environment". While the corrugated fiberboard boxes, steel drums, wooden crates, and pallets have not changed significantly over the pastyears, the shipping requirements of the products have changed with each new generation of both product and shipping technology. As a result, packaging materials have improved to meet the demands of the new technology.

[0004] Refrigerated transportation at one time meant a horse-drawn wagon packed with ice and straw. Super-cooled gases and microprocessor-controlled motors have replaced the earlier, primitive refrigeration techniques. Reliable, temperature-controlled, surface transportation is now available to and from almost anywhere in the world. Trucks and ocean container shipping utilize positive, mechanical refrigeration systems to retard spoilage in transit.

[0005] Such surface transportation is relatively slow, and the shipped goods must have a correspondingly long shelf life. However, many temperature-sensitive products, such as perishable foodstuffs, are time-sensitive as well. Successful long-distance shipping is only feasible where transportation time can be minimized.

[0006] Servicing a worldwide food market required yet another technological development the generous cargo holds of newer, wide-body passenger jet aircraft in the lateand early The drop in airfreight rates heralded by these new jets for the first time permitted the cost-effective transportation of perishable, medium-value commodities such as meat, seafood, and fresh produce.

[0007] Traditionally, such perishable foodstuffs, as well as pharmaceuticals, are cooled prior to shipment, then placed within a thermal insulating material, and shipped with only a modicum of ice or refrigerant to absorb the heat that flows through the insulation. For many years, molded expanded polystyrene ("EPS") containers have been the thermal insulating material of choice. The perishable goods are placed within the EPS containers, which are then in turn placed within small, corrugated shipping boxes.

[0008] EPS containers have been widely used since the lowered airfreight rates first made this form of shipment economically practical. While providing satisfactory insulation qualities as well as being light in weight, EPS also presents several negative characteristics to the shipping industry. EPS is an "expanded," non-compressible material, and consists of a very large number of small air bubbles formed in a polystyrene plastic matrix. EPS"s poor volume efficiency increases shipment costs when transporting the empty containers to the location of their use, as well as causing increased warehousing costs when stored in inventory prior to use.

[0009] While providing reasonable protection from shock impacts during transit, EPS has poor resistance to the application of puncture and shear-loading. EPS easily fractures, requiring the use of an additional plastic liner bag when shipping products with a liquid component, such as ice-chilled, fresh seafood. The lack of such an additional plastic liner risks liquid leakage from the EPS container during shipment, and the resultant expensive damage to aircraft cargo holds or other corrosion-sensitive shipping environments.

[0010] In an effort to avoid EPS and its negative characteristics, a number of shippers have attempted to make use of metalized, radiant barrier bags. Relying on the property of shiny, metalized coatings to reflectively radiate heat energy, such products have found only marginal success as insulated packaging. Although reducing warehousing and breakage expenses, as well as enjoying lower manufacturing costs, many shippers have determined that such radiant bags do not control temperatures over a sufficiently long period of time.

[0011] Ideally, it would be desirable to provide an insulative system having a reliable thermal performance over extended time periods (at leastwhich is leak proof, can be shipped and stored in a manner requiring less space than EPS, and that is fabricated out of materials and in a manner that remains cost-competitive with the EPS insulated box product.

[0012] It is thus an object of the present invention to provide a flexible insulating bag of collapsible design having equal thermal insulation to that provided by EPS. The reduction in storage and shipping volume of the collapsible bag over the EPS container translates into lower costs, enabling world-wide marketing by a single source of supply, permits distributors to economically inventory large quantities of different-sized shipping container bags, and permits shippers to maintain a greater inventory, requiring fewer deliveries as well as economically ship to remote packing locations to cost-effectively service the fresh market from more remote source regions.

[0013] It is a further object of the present invention to provide two reflective surfaces, one inside the hot face to function as a low-emissivity surface and one on the inside of the cold face, functioning as a radiant barrier.

[0014] It is another object of the present invention to provide an inflatable design, permitting collapse of the insulating container for efficient storage, and, when inflated, creating an airspace adjacent the reflective surfaces to empower a further reduction in heat flow, either by lower emissivity or greater reflectivity.

[0015] It is another object of the present invention to provide an alternate intermediate baffle design that incorporates the aforementioned double radiant barrier, in an insulating system that bisects the insulating, inflated chamber in a manner that further inhibits convective heat transfer.

[0016] It is a still further object of the present invention to provide a substrate or carrier layer having a phase change material on one or more surfaces of an intermediate baffle to moderate the transfer of heat energy across the inflated insulating layer.

[0017] It is a further object of the present invention to fabricate such an insulating bag in a manner that utilizes a minimum number of processing steps to form all air-containing and shape-controlling structural features of the insulating bag, including the incorporation of a flat inflation valve and a closure securement system, such as a zip-closure.

[0018] It is another object of the present invention to include one or more uninflated gussets within a bottom panel of the insulating bag to receive and collect melted ice water and any liquid leakage from the shipped products, separating such liquid from the products enhancing freshness and minimizing contamination.

[0019] It is another object of the present invention to fabricate the flexible insulating bags out of film materials using rf welding to enable reliable, high volume manufacturing at low per-unit cost.

[0020] It is another object of the present invention to provide a flexible insulating bag that is inflated with air for normal insulating values, or may be optionally inflated with an inert, low conductivity gas, such as argon, to further enhance insulating performance.

[0021] It is another object of the present invention to permit the collapse of a used insulating bag by deflating same, reducing disposal costs, whether shipped for recycling or on the basis of a reduced amount of landfill volume required if discarded.

Summary of Invention

[0022] These and other objects of our invention are provided by a flexible insulating bag that utilizes an inflatable wall panel construction. A pair of opposed flexible plastic film layers form the walls, and they are inexpensively attached together by rf (radio-frequency) welding. The intricate pattern of attachment seams that connect the pair of film layers is used to define the individual inflatable wall panels, as well as the overall shape of the insulating bag upon its inflation.

[0023] The inflatable walls significantly reduce conductive heat losses through the insulating bag. An enhanced insulative performance can be obtained by replacing environmental air as the inflating gas with an inert, low conductivity gas, such as argon.

[0024] Further insulating enhancement can be obtained by minimizing losses caused by radiant heat transfer. One method of achieving lower radiant thermal losses utilizes a metalized reflective layer formed on one of the surfaces of the plastic film. When configured in a manner resulting in the placement of the reflective layer on the inner surface of the outer wall (which is normally the "hot face"), a low emissivity surface is obtained. A similar metalized surface provided on the opposing, inner surface of the interior wall film, normally the "cold face,"acts as a radiant barrier.

[0025] An alternate strategy for minimizing radiant thermal losses (as well as convective heat losses), makes use of baffles placed within the inflated wall panels. One type of baffle relies upon a stiffened material, and will, if carefully dimensioned, self-center between contracting adjacent attachment seams during inflation of the wall structure. Emplacement of the stiffened baffles within the wall structure during the fabrication thereof may be obtained by providing a sheet of baffle material having slots formed therein that dimensionally conform in both size and location to the rf welding seams. The slotted baffle material is then received between the pair of plastic film layers prior to rf welding.

[0026] An alternative baffle material makes use of a continuous sheet of a flexible film having both surfaces metalized and rf-weldable. When placed between the plastic, outer wall film layers and alternately attached to interior and exterior liner walls, the flexible baffle material will kink during inflation of the wall. Such alternate attachment seams can easily be obtained by interweaving the flexible baffle sheet through a comb-shaped release form that is withdrawn prior to the making of a final weld to close off the wall panels.

[0027] The optional utilization of stripes of a micro-encapsulated phase change material formed on the surface of the baffle provides a further barrier to heat flow through the inflated insulating wall panel. Included within a carrier substrate, the phase change material absorbs heat energy as it changes state, blocking further heat flow until such phase transition is complete. Acting in a similar manner to such known cargo packing materials as dry and wet ice, the micro-encapsulation enables use of a phase change material within the insulated material, while maintaining the structural integrity and functionality of the remaining features of the inflated insulating wall panel structure.

[0028] The use of rf welding enhances the manufacturing efficiencies enjoyed by the use of plastic film layers from which to fabricate the insulated bag. When appropriately pre-folded prior to welding, the plastic film layers and the detailed rf welding pattern jointly cooperate to minimize the number of welding passes required. Bag formation with an asymmetrical welding pattern requires two separate passes, with the second to secure the side panels together, forming the boxed ends.

[0029] Alternatively, the use of a symmetrical, single-pass welding pattern permits the formation of an enclosed bag, including all side sealing seams, and a double-flap instead of a single-flap enclosure lid. The inflatable portion of a single welding pass design is defined by a seam pattern that does not encompass the entire area of the opposing plastic film layers. Adjacent to the symmetrically-formed container floor portion are a pair of uninflated floor gussets. Upon opening the interior portions prior to receipt of the cargo to be shipped, the bottom gussets form a liquid reservoir suitable for receiving and holding any liquids as might drain from the cargo area. Such liquid drainage might be given off by the cargo itself, or result from melt water from the cooling ice. Removal of such liquids from immediate contact with the shipped cargo reduces spoilage and extends the shipping life of the cargo.

[0030] Some further objects and advantages of the present invention shall become apparent from the following description, claims, and drawings.

Brief Description of Drawings

[0031]Figure 1 is an exploded perspective view, with portions in phantom, showing an inflatable insulating shipping box liner receiving a seafood product for shipment, and placed within an outer shipping container in accordance with the present invention; Figure 2 is a cross-sectional view, taken along line 2-2 in Figure 1 showing an inflatable insulating shipping box liner in accordance with the present invention; Figure 3 is a partial cross-sectional view taken along line 3-3 of Figure 2 showing the manner in which two panels of an inflatable, insulating shipping box liner are joined together; Figure 4 is a top plan view, showing a weld pattern formed on a plastic substrate during the fabrication of an inflatable insulating shipping box liner in accordance with the present invention; Figures 5A-D are front and side schematic views depicting the manner in which the welded plastic substrate of Figure 4 is fabricated into an insulating box-like structure; Figure 6 is a partial cross-sectional view showing the manner in which a baffle material is received within the inflatable pattern formed in the plastic substrate shown in Figure 4; Figure 7 is a partial top plan view of a baffle material, showing a cut-out pattern corresponding to the weld pattern shown in Figure 4; Figure 8 is an exploded perspective view, with portions in phantom, showing a flexible baffle sheet as received upon a comb-shaped release form in accordance with the present invention; Figure 9 is an exploded perspective view, with portions in phantom, showing a flexible baffle sheet and comb-shaped release form as received between an inner and an outer film layers in accordance with the present invention; Figure 10 is a perspective view, with portions in phantom, showing a flexible baffle sheet and comb-shaped release form after attachment of the baffle sheet to the inner and outer film layers in accordance with the present invention; Figure 11 is a perspective view, with portions in phantom, showing a partially separated pair of inner and outer film layers with a flexible baffle sheet extending in an alternating manner therebetween, with a comb-shaped release form in the process of being removed therefrom in accordance with the present invention; Figure 12 is a perspective view, with portions in phantom, showing a separated pair of inner and outer film layers with an intermediate flexible baffle, after removal of the comb-shaped release form in accordance with the present invention; Figure 13 is a top plan view showing a weld pattern in a plastic substrate that defines the inflated portion of an alternative insulating shipping box liner in accordance with the present invention; Figure 14 is a perspective view showing the alternative inflatable insulating shipping box liner of Figure 13 in accordance with the present invention; Figure 15 is a cross-sectional view, taken along line 15-15 in Figure 14 showing an alternative inflatable insulating shipping box liner in accordance with the present invention; Figure 16 is a cross-sectional view, taken along line 16-16 in Figure 14 showing the sequence of insulating bladders defining an outer periphery of the inflatable insulating shipping box liner in accordance with the present invention; Figure 17 is a perspective view showing an alternative inflatable insulating shipping box liner having a honeycomb-baffle container liner in accordance with the present invention; Figure 18 is a cross-sectional view, taken along line 18-18 in Figure 17, showing the honeycomb-baffle container liner in accordance with the present invention; Figure 18A is a cross-sectional view similar to Figure 18, showing an alternative embodiment of an inflatable insulating shipping box liner making use of stripes of a phase change material on a baffle surface; Figure 19A is an enlarged, partial cross-sectional view of the encircled area of Figure 18B, showing stripes of a phase change material located on a single side of a baffle in accordance with the present invention; Figure 19B is an enlarged cross-sectional view similar to Figure 19A, showing stripes of a phase change material located on both sides of a baffle in accordance with an alternative embodiment of the present invention; Figure 20 is an exploded perspective view with portions in phantom, similar to Figure 8, and showing a flexible baffle sheet having a striped array of phase change material on one or both sides thereof, as received upon a comb-shaped release form in accordance with an alternate embodiment of the present invention; Figure 21 is a perspective view, with portions in phantom, showing an intermediate flexible baffle having a striped array of a phase change material formed thereon, the baffle attached to and located between inner and outer film layers after removal of the comb-shaped release form in accordance with the present invention; Figure 22 is an enlarged view of a flexible baffle substrate having a stripe of a phase change material formed thereon; Figure 23 is a partial enlarged perspective view showing individual film layers and a sealing tool as positioned prior to forming heat sealed attachment segments in accordance with an alternative embodiment of the present invention; Figure 24 is an enlarged partial perspective view of the multiple layers of Figures 23 shown after the selective attachment of certain of the layers to one another by heat sealing in accordance with an alternative embodiment of the present invention; and Figure 25 is a graph comparing temperature changes over time experience by cargo insulated using a liner employing the present invention and a competitive technology.

Detailed Description

[0032] Reference is now made to the drawings wherein like numerals refer to like parts throughout. An inflatable insulating shipping box liner10 is depicted in Figure1 as received within a transport box bottom 14. A pair of gussets 16 formed at each end of the transport box bottom 14 are preferably provided to minimize the likelihood of any liquid leakage from within the transport box bottom 14.

[0033] A transport box top 18 is received by the transport box bottom 14 in a fully telescoping manner, again minimizing the opportunity for the leakage of liquid from the contents carried within the transport box. Additionally, in a conventional manner the transport box bottom and top 14, 18 are both waxed to preserve their structural integrity against damage caused by liquids that have either leaked from the interior insulating shipping box liner or from liquids wetting an outer surface or surfaces thereof.

[0034] The inflatable insulating shipping box liner 10 includes a front wall 22 a pair of side walls 24a, 24b, a rear wall 26, a floor 28, and a top or covering flap 32, which together define an interior container space 34 suitable for the transport of perishable products, such as a fish 56 depicted in Figure 1. The insulating shipping box liner 10 is preferably inflated once placed within the transport box bottom 14, prior or just after placement of the perishable product within the interior container space 34.

[0035] Air is introduced into the interior space lying within each of the various structures of the insulating shipping box liner 10 by an inflating valve 38. All structural portions of the insulating shipping box liner 10 are in fluid communication with one another, permitting air entering through the inflating valve 38 to flow into and inflate all portions of the inflating bag 10. A plurality of different-shaped inflation seams 42 govern the manner in which the various component portions of the insulating shipping box liner 10 inflate as well as their resulting configuration. The inflation seams 42 likewise define a plurality of inflated tubes that are of suitable cross-sectional dimension to provide the structural rigidity required of the various panel members of the insulating shipping box liner 10.

[0036] The function of the inflation seams 42 is best described with reference to Figure 2. As is the case for each of the sections forming the insulating shipping box liner 10 the front wall 22 consists of an inner material layer 52 and an outer material layer 54. Upon the admission of air through the inflating valve 38 (or an inert gas such as argon, should greater insulating values be desired), the inner and outer material layers 52, 54 are separated by the incoming gas, and "balloon out." Along the inflation seams 42 the inner and outer material layers 52, 54 are joined to one-another, preventing their separation by the incoming charging gas.

[0037] In this manner, the placement of the inflation seams 42 defines the shape of the inflated portions of the insulating shipping box liner 10 In Figure 2 the latitudinal, spaced-apart inflation seams 42 create a vertical arrangement of horizontally-extending inflated tubes. Similar arrangements of the inflation seams 42 in the floor 28, the rear wall 26, and the top or covering flap 32 results in similar inflated horizontal tubular structures that extend the length of the insulating shipping box liner 10. The side walls 24a, 24b present a variation on this theme, with each consisting of a joined arrangement of three separate lateral panels 58a, 58b, 58c.

[0038] A first and a second of the lateral panels 58a, 58b are trapezoidal-shaped extensions of the front and rear walls 22, 26. A vertically-extending inflation seam 42 (shown in Figure 1) separates the first and second lateral panels 58a, 58b from the adjoining portions of the respective front and rear walls 22, 26 and forms a side edge when the insulating shipping box liner 10 is inflated. The third lateral panel 58c is formed as a triangularly-shaped extension from the floor 28 with a linear inflation seam 42 (shown in Figure 1) also separating these two panels. The adjoining lateral edges of the first, second, and third lateral panels 58a, 58b, 58c are joined together forming a tri-segment attachment seam 64 (Figures 2and 3).

[0039] The lateral panels 58a, 58b, 58c each present a reduced inflated area, and thus a sequence of spaced longitudinal inflation seams 42 are not required. Instead, a centrally-located "U"-shaped inflation seamis provided each of the lateral panels 58a, 58b, 58c. In a preferred embodiment, the base of the "U"in each of the panels is directed toward the angular side of the lateral panel or, in the case of the triangular, third lateral panel 58c toward the apex of the triangle. As so positioned, the inflation seams 42 provide the appropriate restriction for limiting the balloon effect between the inner and the outer material layers 52, 54 in the lateral panels 58a, 58b, 58c of the inflatable insulating shipping box liner 10 to a specified inflated thickness of, by way of example and not limitation, one inch (1").

[0040] The extent or area over which the inner and outer material layers 52, 54 inflate is defined by a sealing seam 66 that continuously extends about the outer periphery of each of the individual panels making up the inflatable insulating shipping box liner 10. The air or inert gas is admitted through the inflating valve 38 and into the portion of the insulating shipping box liner 10 lying inside of the sealing seam 66. Once admitted, the sealing seam 66 prevents the gas from escaping, resulting in the inflation of this sealed portion of the insulating shipping box liner 10.

[0041] As shown in Figure 2 a reinforcement seam 68 is spaced interiorly from and runs parallel to the sealing seam 66 along the top portion of the inflation bag 10. The reinforcement seam 68 acts to stiffen the upper portions of the insulating shipping box liner 10, as well as to better define the opening of the insulating shipping box liner 10 and thereby assist during the loading and unloading thereof. Exterior of the sealing seam 66 is located an uninflated flap 72. When the cover 32 is placed over the interior container space 34, the uninflated flaps 72 located circumferentially thereabout can be folded over the edges of the cover 32 to provide an additional measure of thermal sealing protection.

[0042] A presently preferred manner for fabricating the insulated bag 10 is shown in Figures 4 and 5A-D. Turning first to Figure4, a multi-layer sheetform substrate 82 has a multiple seam pattern 84 formed thereon. The sheetform substrate 82 preferably consists of two layers of a plastic material, and the seam pattern 84 is preferably formed thereon by radio-frequency welding. As so formed, the seam pattern 84 comprises both the individual panel construction of the insulating shipping box liner 10 as well as the inflation pattern thereof, as just discussed.

[0043] Each lateral portion of the seam pattern 84 defines the lateral panels 58a, 58b, 58c that, when attached together, form the pair of side walls 24a, 24b for the insulating shipping box liner 10. The seam pattern 84 also defines a series of rectangular sections that, when assembled, form the cover 32, the front and rear walls 22, 26, and the floor 28. Additionally, although not labeled to maintain drawing clarity, the initial fabrication step also forms the pattern of inflation seams42, the sealing seams 66, and the reinforcement seams 68.

[0044] Four pairs of the inflation seams 42 are more closely spaced than is typical for the other inflation seams 42 and thereby form four folding seams 88 that simplify the succeeding fabrication procedures as well as form the bottom front and rear bag folding edges, and enable the easy closure of the cover 32. As shown in Figure 4 a floor-folding seam 88a is centrally formed in the center of the floor 28 and is used to assist in the fabrication of the finished bag construction as is hereinafter discussed. A pair of parallel, edge-folding seams 88b are equally spaced-apart on either side of the floor seam 88a and form the front and rear bottom edges in the finished insulating shipping box liner 10. Finally, a cover-folding seam 88c is formed at the joinder of the cover 32 and the rear wall 26, permitting the easy folding of the cover 32 even after inflation of the insulating shipping box liner 10.

[0045] Upon removal of the excess substrate material lying beyond the seam pattern 84 shown in Figure 4, the remaining cut-out is ready for the final fabrication operations, which are best described with reference to Figures 5A-5D. In Figure 5A the front and rear walls 22, 26 are brought together by first folding on the edge-folding seams 88b and then collapsing together the floor 28 by oppositely folding on the floor-folding seam 88a. As properly folded, both resulting halves of the floor 28 are placed between the now-adjoining front and rear walls 22, 26(also shown in Figure5B).

[0046] As so positioned, the lateral panels 58 engage one another along each of their respective lateral edges (best shown in Figure 5C). The attachment seams 64 may now be formed, again, preferably by radio-frequency welding when plastic sheet substrates are used. In such an instance, a release sheet 92 is appropriately inserted between the lower half-panels of the floor 28 to prevent the inadvertent attachment of the angled edges of the front and rear wall lateral panels 58a, 58b to one another instead of to only the adjoining lateral edges of the floor lateral panel 58c during this second welding operation.

[0047] The resulting inverted "Y"-shaped attachment seams 64 are best shown in Figure 5C, and illustrate the formation of the side walls 24a, 24b out of the three separate lateral panels 58a, 58b, 58c. Upon once again separating the front wall 22 from the rear wall 26, the now-attached separate lateral panels 58 expand to form the side walls 24. The resemblance of the insulating shipping box liner 10 to a box-like structure is now apparent, requiring only inflation prior to its use.

[0048] In a preferred embodiment, the inner material layer 52 is metallized to function as a radiant barrier and the outer material layer 54 is metallized to function as a low emissivity surface, greatly enhancing the insulating qualities of the inflatable insulating shipping box liner 10 in comparison to the insulative effect of inflation alone. Since considerable manufacturing economies are obtained by relying upon radio frequency welding, and with thermal performance significantly improved by metallizing the inner and outer material surfaces 52, 54, the materials selected for fabricating these layers must be capable of rf welding and be metallized. It has proven to be somewhat difficult to reconcile these two features.

[0049] Although materials testing continues, the most likely solution presently appears to be a three-sheet laminate consisting of an outer blended polyolefin film layer containing polyethylene and either ethylene vinyl acetate (EVA) or ethylene methyl acrylate (EMA) to enhance its RF weldability, an inner metallized polyester film, and a second blended polyolefin film layer containing polyethylene and EVA or EMA to form the laminated structure.

[0050] In addition to its ability to be RF welded, the polyolefin film also provides good puncture resistance. Unfortunately, polyethylene film does not metallize well, and it does not resist stretching which potentially permits the overfilling of the inflatable insulating shipping box liner 10. Polyester film, in addition to being readily metalized, does not stretch yet provides good burst strength. Together, this laminate forms a firm packaging material, with the inflation thereof through a flat, plastic valve such as those manufactured by Sealed Air Corporation of New Jersey for use in their air-filled packaging systems.

[0051] Based upon some early prototype work, producing such a laminate has proven to be somewhat difficult to accomplish in the large quantities required for its economical use in the present packaging system. If such a laminate is not uniform when produced in larger quantities, its failure, even on a "spot"or partial basis, would significantly erode the beneficial insulating qualities of the inflatable insulating shipping box liner of the present invention.

[0052] A presently preferred alternative insulating system instead relies upon interior baffles that are provided with a radiational barrier surface. Turning now to Figure 6 a pair of internal baffles 96 are shown received within an adjoining pair of inflated insulated cells 98 of the insulating shipping box liner 10. These internal baffles 96 are depicted as centered within the insulated cells 98, which occurs upon inflation as a result of the careful dimensioning of the internal baffles 96. Specifically, a lateral dimension of the internal baffles 96 is selected such that upon the inflation of the insulating cells 98, the resulting balloon-expansion of the inner and the outer material layers 52, 54 causes a contraction of the parallel seams adjacent to both sides of the inflation cells 98, with the internal baffles 96 self-centering in the widest part of the insulating cells 98.

[0053] A presently preferred technique for placement of the internal baffles 96 within the individual insulating cells 98 formed in the insulating shipping box liner 10 is to form the baffle material as a single cut-out that can be received between the inner and outer material layers 52, 54at the time of fabricating the insulating shipping box liner 10. As shown in Figure 7, such a scheme results in a baffle cut-out sheet 101 having a plurality of inflation seam openings 103 formed therein at locations corresponding to each location in which the inflation seams 42 are formed in the sheetform substrate 82, as well as a plurality of folding seam openings 105formed at locations corresponding to the folding seams 88 (compare Figures 4 and 7).

[0054] Attachment of the top and bottom material layers of the sheetform substrate82 by RF welding thereby integrates the inner and outer material layers 52, 54 with the intermediate baffle cut-out sheet 101 creating a single, multi-layered material. Subsequently folding and RF welding a second time completes the insulating shipping box liner 10 in the manner previously discussed (see Figures 5A-D).

[0055] Initial studies have indicated the suitability of a kraft paper and foil paper laminate as the baffle material. It is light in weight and easily formed into the complex pattern required of the baffle cut-out sheet 101. Also, by providing a foil paper laminate on both sides of the kraft paper, a double radiant barrier is formed within each of the inflated insulating cells 98. Lamtite of New Jersey manufactures such a product under the name "Foil-Kraft-Foil."

[0056] In another preferred embodiment, the baffle may be a continuous sheet that is welded in place during the fabrication of the insulating liner. The arrangement of its welds forms a plurality of walls that together create a honeycomb-type structured layer out of the continuous sheet, eliminating the requirement that the baffle be die-cut in a manner mimicking the pattern of the subsequently-welded seams. Such a baffle material must be metallized and RF weldable on both sides, and when attached to alternate interior and exterior liner walls, will kink or separate during inflation of the liner, resulting in a honeycomb structure that further increases the thermal efficiency of the inflatable insulating liner. The thermal properties and characteristics of such a honeycomb structure are described in Griffith, et al., U.S. Patent No. 5,270,092 owned by the Lawrence Berkeley National Laboratory of the University of California.

[0057] A presently preferred method of obtaining such a structure within an insulating liner in accordance with the present invention is depicted in Figures 8-12. In Figure 8 a baffle sheet 107 is fabricated out of a material such as polyethylene film, metalized on one side, with that same side then laminated to a second layer of polyethylene film. The baffle sheet 107 is woven through a comb-shaped release form 109 with the baffle sheet 107 covering alternating fingers of the release form 109 as is depicted in Figure 8. The interwoven comb-structure is then placed between the inner material layer 52 and the outer material layer 54 (shown in Figure 9).

[0058] A plurality of spaced weld lines 111 are depicted in Figure 10, with each of the weld lines 111 centrally located over each finger of the release form 109. With the baffle sheet 107 alternating over and under each of the fingers of the release form 109, as shown with the release form 109 partially withdrawn in Figure 11, the baffle sheet 107 attaches to the inner material layer 52 by a weld 111 at those locations where it overlies the fingers. Similarly, where the baffle sheet 107 is woven under the fingers, it is attached by a weld (not shown) to the outer material layer 54, creating the alternating lines of attachment shown in Figure 12. A final weld is then made to close off the interior portion.

[0059] Returning to the insulating shipping box liner, the fabrication process depicted in Figures 4 and 5A-5D requires two separate RF welding operations ("2-Hit Design"). In a preferred embodiment depicted in Figure 13, a single RF weld creates a "1-Hit" insulating shipping box liner 115 (shown in Figure 14). The sheetform substrate 82 is laid out identically to that previously described, including the insertion of the baffle cut-out sheet 101 (not shown) where this additional insulation is desired. The sheetform substrate 82 is then folded upon itself, along a fold line 117. A release paper (not shown) having dimensions 1/4-inch less in width than the sheetform substrate is inserted between the folded sheets, and is sufficiently long to extend out therefrom, preventing the top and bottom edges of the substrate from being adhered together during the welding operation that follows.

[0060] Preferably, as with the "2-Hit Design,"an RF welding operation (not depicted in the Figures) is used to form a "1-Hit"seam pattern 119 within the folded sheetform substrate 82. In Figure 13 the non-folded outline of such a pattern is shown, which is symmetrical about a linear axis formed by the fold line 117. The "1-Hit"seam pattern 119 defines the perimeter of the inflated portion of the "1-Hit"insulating shipping box liner 115. The outer periphery forms a pair of lateral seams of attachment 120, which attach the overlying sheetform substrates except at an opposing pair of upper and lower longitudinal edges 121, 123.

[0061] The symmetrical folding of the sheetform substrate prior to RF welding results in the formation of a pair of front/back sidewall sections 127a, 127b.The floor is likewise separated by the fold line 117 into a pair of front/back floor sections 131a, 131b. Finally, the seam of attachment 120 does not extend along the upper and lower longitudinal edges 121, 123 thereby forming a pair of front/back cover sections 135a, 135b. The location of each of such sections after RF welding is depicted in Figure 14.

[0062] As noted previously, the inflatable portion defined by the "1-Hit"seam pattern 119 does not encompass the entire area of the sheetform substrate 82. The uninflated portion adjacent to the front/back floor sections 131a, 131b forms a pair of floor gussets 141 (only one shown in Figure 14). A pair of partial cover gussets 143 are formed adjacent to the front/back cover sections in a similar manner, excepting a non-joined portion that reflects the lack of a seam of attachment along the upper and lower longitudinal edges 121, 123. The floor gusset 141 and the partial cover gusset 143 assist in providing additional sealing protection against liquid leakage from within the "1-Hit" insulating shipping box liner. Additionally, by forming a reservoir to remove from product interface liquids draining from the product, whether as a result of melting ice or natural product exudate, the gusset reservoir enhances product freshness and shelf life.

[0063] For purposes of clarity, the inflation seams and attachment seams have been omitted from the "1-Hit"design layout shown in Figure 13. As is shown in Figures 15 and 16, however, the inflation pattern formed in the "1-Hit" insulating shipping box liner 115 is similar, although less complex than with the "2-Hit" insulating shipping box liner 10 of Figure 1. Without the lateral panels 58 forming the side walls 24a, 24b the insulating shipping box liner 115 requires only a latitudinal pattern of inflation seams 42.

[0064] Upon the inflation thereof, a series of vertically-arranged, horizontally-extending insulating tubes results, with each tube extending from and between the pair of lateral seams of attachment 119 (see Figure 16). In a preferred embodiment, a plurality of corner fold seams 147 (shown in Figure 16) are formed adjacent to the front/back sidewall sections 127a, 127b during the fabrication of the "1-Hit"insulating shipping box liner 115. The corner fold seams 147 permit the easy bending of the insulating tubes when transitioning from the front and rear walls 22, 26 to the side walls 127.

[0065] When the honeycomb-type structured layer utilizing the single sheet baffle discussed in association with Figures 8-12 is used to create a shipping container, one such container, a honeycomb-baffle container liner 151 is shown in Figures 17 and 18. In a similar construction to the 1-hit insulating shipping box liner 115, the front and back cover sections 135a, 135b thermally secure the interior containment space of the honeycomb baffle container liner 151.

[0066]Figure 18 best depicts the manner in which the continuous baffle sheet 107 forms the honeycomb sections as it alternates its seams of attachment between the inner material layer 52 and the outer material layer 54. At each seam of attachment, an inner inflation seam 42A or an outer inflation seam 42B is created. Where the continuous baffle sheet 107 is provided a metalized, reflective surface, a continuous radiant barrier is formed within an inflated envelope, placing the barrier adjacent the air space required for its maximum effectiveness.

[0067] Other baffle materials are feasible, and a further preferred embodiment contemplates the use of a "phase change" material in a baffle, either replacing the kraft paper substrate or as another layer formed therein. In one contemplated embodiment, the kraft paper is replaced by a thermoset polyurethane foam, with a radiant outer barrier formed on its outer surface, such as by the attachment of aluminum foil layers.

[0068] Dispersed within the foam layer are molecules selected to undergo a phase change in the appropriate temperature range. This range can be varied by the manufacturer of the phase change molecules to maximize the performance of thermal protection for various shipping environments. In changing phases, these phase change molecules absorb heat from the environment. By so doing, these molecules significantly reduce the transfer of heat through the baffle material, enhancing the insulating qualities obtained over the radiant barrier alone.

[0069] Outlast Technologies, Inc., of Boulder, Colorado, has developed a line of phase change materials that are in a micro-encapsulated form. In addition to being placed within fibers and fabrics, other substrates or carriers can be used to permit screen printing the material in patterns and arrays. Turning now to Figure 18A, a phase change material layer 161 is shown as formed on (or carried by at) selected locations of the baffle sheet 107. Although the phase change material layers 161 are shown in Figure 18A as formed only on those surfaces of the baffle sheet 107 as face the outer material layer 54 (see also Figure 19A), this is exemplary only. As is shown in Figure 19B, it is also contemplated within the present invention to place the phase change material layers 161 on both the inner and outer surfaces of the baffle sheet 107.

[0070]Figure 20 illustrates a possible manner of fabricating the phase change material layers 161 within the inflatable insulating liner construction. A baffle sheet 107a having a striped array 165 of a phase change material formed on one side thereof (or on both sides of a baffle sheet 107b) is received by the comb-shaped release form 109. As was the case in the context of the Figure 8 discussion, the baffle sheet 107a is received by the release form 109 in an alternating manner, over and under each of the fingers thereof.

[0071] Turning now to Figure 21, after attachment of the baffle sheet 107 to the inner material layer 52 and the outer material layer 54 by the plurality of weld lines 111, the comb-shaped release form 109 is removed. The striped array 165 is so arranged as to present the layer of phase change material on the surface of the baffle sheet lying between the inner and outer material layers 52, 54. No such layer of phase change material is placed at locations of attachment (the weld lines 111). As noted previously, and as is illustrated in Figure 22, the striped array 165 consists of a plurality of micro-encapsulated phase change material in a carrier or substrate. In this manner, the phase change material remains encapsulated, regardless of the change in state or phase. For example, if water were selected as the phase change material, and frozen prior to use in a shipment, its change to a liquid (or gas) phase would be contained within the capsule, thus maintaining the thermal integrity of the inflated insulating liner.

[0072] Fabrication of the honeycomb baffle container 151 as depicted in Figures 20 and 21 makes use of a plurality of weld lines 111 obtained through the use of release forms and rf radiation. A presently preferred fabrication process makes use of thermally-formed welds, utilizing the structure shown in Figure 23.

[0073] A plurality of material layers are shown in Figure 23 laying between a heated tool 171 and an impact surface 173. Layers "A"and "F"form the outer layers (corresponding to the inner and outer material layers 52, 54 not shown in Figures 23 or 24), and preferably comprise a heat-sealable 3.0 - 3.5 mil polyolefin. The remaining layers "B"through "E" are also fabricated out of this same polyolefin; however, each are preferably 1.0 to 1.5 mil thick having a maximum Dyne level of 35. A plurality of metal stripes 175 forming an array is provided across one or both sides of the film surface, each with an optical density of 1.6 (minimum).

[0074] A presently preferred metal is aluminum, and strip placement is critical to the formation of the reflectorized baffles. In each instance, a length of between 0.5"-1.5"(wide) strip of metal is followed by a length of a clear strip of between 0.15"-0.4"(wide) exposed polyolefin surface, with the width of this repeating pattern of between 0.65"-1.9".

[0075] While this pattern is followed for each striped metal pattern, each pattern is laterally shifted relative to adjacent layers. Thus, for "Typical "A" Position"in Figure 23 the outer layer "A" overlies a clear strip on both surfaces of layer "B", a metallized strip on one side of layer "C"and a clear strip on the other, a clear strip on the top side of layer "D" and a metallized strip on the bottom, a clear strip on both top and bottom of layer "E", and a clear strip on top of the final layer "F".

[0076] "Typical "B" Position"in Figure 23 lies one-half cycle removed from "Typical "A" Position", and the vertical match up is entirely different. The bottom surface of layer "A" faces a metal strip on the upper surface of layer "B"and a clear strip on the bottom surface, a clear upper surface on layer "C"and a metal strip on the bottom surface, a clear strip on both the upper and lower surfaces of layer "D", a clear upper surface on layer "E"and a metal strip on the bottom, and a clear upper surface on the final layer "F".

[0077] Such alternation of clear and metal surfaces is required to form the various baffles in the multi-layer inflatable. Upon pressing down on the layers as shown arranged in Figure 23 with the heated tool 171, provided the appropriate temperature is maintained; only adjacent clear strips will adhere to one another, and the metal strips function as release surfaces relative to an adjacent clear surface. Such vertical compression in turn results in creating an array of alternating seams of attachment joining adjacent outer and intermediate layers. These seams of attachment form, in effect, an interconnected web. Upon inflation, this web expands to form a multi-layer baffle construction having a plurality of individual baffle chambers, which is shown in Figure 24.

[0078] Following the above "rules of adhesion,"it is observed that for "Typical "A" Position"the clear lower surface of layer "A"adheres to the clear upper surface of layer "B" but not to the metal strip 175 on the upper surface of layer "C". The clear strips on bottom layer "C"and top layer "D"adhere to one another, but not the metal strip 175 on the bottom of layer "D" to the clear strip on the top of layer "E". The opposing clear strips on the bottom of layer "E"and the top of layer "F"adhere to one another, completing the vertical extent of "Typical "A" Position". With each diagonal side considered to be a "baffle", there are four baffles extending from layer "A"to layer "F"along "Typical "A" Position".

[0079] "Typical "B" Position"forms the alternative structure, with the bottom surface of layer "A"not adhering to the top metal strip 175 of layer "B", and the clear bottom of layer "B" adhering to the clear top surface of layer "C". The bottom metal strip 175 of layer "C"does not adhere to the clear upper surface of layer "D", while the clear lower surface adheres to the clear upper surface of layer "E". Finally, the bottom metal strip 175 of layer "E"does not adhere to the upper clear surface of final layer "F". It can be appreciated that such alternating layers can continue where a larger number of baffles are desired.

[0080] Additional disclosure regarding this manner of manufacture may be found in co-pending U.S. Patent Application Serial No. 09/683,392, Filed December 20, 2001 (published on June 27, 2002, as U.S. Application No. US-2002-0081041-A1), entitled: "INFLATABLE INSULATING LINERS FOR SHIPPING CONTAINERS,"the disclosure of which is hereby incorporated herein by reference. In the context of the present invention the striped array of phase change material 165 can easily be introduced into the careful spacings required for the thermal-sealing fabrication displayed in Figures 23 and 24.

[0081] The majority of shipping containers used for fresh flowers, seafood, produce and the like measure 24 inches by 14 inches, and are 12 inches in height. A suitable "2-Hit"inflatable insulating shipping box linerwould have (when inflated) a floor of measurements 24 inches by 14 inches, front and rear walls of height 12 inches, and a cover having dimensions of 24 inches by 14 inches. A suitable thickness (when inflated) for maintaining a desired temperature for 48 hours is 1 inch. A "1-Hit"insulating shipping box linerwould have similar dimensions, except that each of its two covers would have dimensions of 24 inches by 7 inches. The present invention of dimensions suitable for such a typical shipping box would measure 38 inches by 27 inches by 1/2 inch thick, when deflated for shipment. Having cubic dimensions of only .30 cubic feet during shipment, the insulating liner of the present invention compares quite favorably to the much more bulky EPS shipping container that would require 2.25 cubic feet for supply shipment and inventory storage.

[0082] The graph of Figure 25 compares internal "product"temperatures over time as occurred between an inflatable insulating shipping box liner placed within an outer corrugated shipping container and an EPS shipping container similarly placed within such a shipping container. The ambient temperature varies over time as is indicated in Figure 25.

[0083] Our invention has been disclosed in terms of a preferred embodiment thereof, which provides an improved insulating cargo containment system that is of great novelty and utility. Various changes, modifications, and alterations in the teachings of the present invention may be contemplated by those skilled in the art without departing from the intended spirit and scope thereof. It is intended that the present invention encompass such changes and modifications. 

Claims 1.An inflatable insulating panel comprising: a multi-layer sheetform substrate having at least one intermediate layer therein, said intermediate layer attached in an alternating manner to a pair of adjacent ones of said multi-layer sheetform substrate such that the three layers cooperatively form a honeycomb-type structure having a plurality of walls; an outer seam extending about a peripheral edge of said sheetform substrate defining an envelope; a phase change material carried by said intermediate layer at a plurality of locations corresponding to multiple ones of said plurality of walls of said honeycomb-type structure; a valve attached to said envelope and in fluid communication with said honeycomb-type structure, whereby inflation of said honeycomb-type structure may selectively be made to occur. 2.An inflatable insulating panel according to Claim 1, wherein said phase change material is carried by said intermediate layer in a non-continuous manner. 3.An inflatable insulating panel according to Claim 2, wherein said plurality of locations of said phase change material comprises an array. 4.An inflatable insulating panel according to Claim 3, wherein said plurality of locations of said phase change material comprises a striped array. 5.An inflatable insulating panel according to Claim 4, wherein there are multiple intermediate layers, each having a striped array of a phase change material carried thereon. 6.An inflatable insulating panel according to Claim 1, and further comprising: an inflation seam continuously formed within said envelope, said inflation seam defining a plurality of inflatable side, top, and bottom panels, whereby upon inflation, said plurality of panels cooperate to form a sealed container. 7.An inflatable insulating panel according to Claim 6, and further comprising a pair of uninflatable panels defined by said inflation seam, each of said uninflatable panels extending between a lateral edge of said inflatable bottom panel and between opposing lateral edges of an adjoining pair of inflatable side panels. 8.An inflatable cargo container liner comprising: an inner material layer and an outer material layer attached to one another in a manner defining a sheetform envelope having a pair of opposed inner walls; an inflation seal coupling said inner material and outer material layers in a manner to form a plurality of interconnected inflatable chambers; a baffle comprising a continuous material layer disposed between said inner and outer material layers and attached to each in an alternating manner that defines a plurality of walls forming a honeycomb-type structured layer; a phase change material layer formed on said baffle at selected locations thereof; and a valve in fluid communication with said plurality of interconnected inflatable chambers. 9.A cargo container liner according to Claim 8, wherein said phase change material layer is formed on one or more of said plurality of walls forming said honeycomb-type structured layer. 10.A cargo container liner according to Claim 9, wherein said inflation seal couples said inner and outer material layers in a manner forming both said plurality of interconnected inflatable chambers and a plurality of uninflatable gussets. 11.A cargo container liner according to Claim 10, wherein said plurality of uninflatable gussets are distributed among said inflatable chambers in a manner such that upon inflation of said sheetform envelope said uninflatable gussets and said inflatable chambers cooperate to provide a substantially rectangular footprint for said cargo container liner. 12.A cargo container liner according to Claim 8, and further comprising a plurality of material layers disposed between said inner material layer and said outer material layer. 13.A cargo container liner according to Claim 8, wherein said baffle is one of said plurality of material layers, and wherein said baffle is attached to an adjacent pair of said plurality of material layers in an alternating manner defining said plurality of walls forming said honeycomb-type structured layer. 14.A cargo container liner according to Claim 13, and further comprising more than one said baffle disposed between said inner and said outer material layers, wherein said phase change material layer is formed on at least one of said more than one said baffle. 15.A cargo container liner according to Claim 14, wherein said phase change material layer is formed on one or more of said plurality of walls forming one or more of said honeycomb-type structured layers. 16.A cargo container liner according to Claim 15, wherein said inflation seal couples said inner and outer material layers in a manner forming both said plurality of interconnected inflatable chambers and a plurality of uninflatable gussets. 17.A cargo container liner according to Claim 16, wherein said plurality of uninflatable gussets are distributed among said inflatable chambers in a manner such that upon inflation of said sheetform envelope said uninflatable gussets and said inflatable chambers cooperate to provide a substantially rectangular footprint for said cargo container liner. 